A data selection method for matrix effects and uncertainty reduction for laser-induced breakdown spectroscopy

Severe matrix effects and high signal uncertainty are two key bottlenecks for the quantitative performance and wide applications of laser-induced breakdown spectroscopy(LIBS).Based on the understanding that the superposition of both matrix effects and signal uncertainty directly affects plasma parameters and further influences spectral intensity and LIBS quantification performance,a data selection method based on plasma temperature matching(DSPTM)was proposed to reduce both matrix effects and signal uncertainty.By selecting spectra with smaller plasma temperature differences for all samples,the proposed method was able to build up the quantification model to rely more on spectra with smaller matrix effects and signal uncertainty,therefore improving final quantification performance.When applied to quantitative analysis of the zinc content in brass alloys,it was found that both accuracy and precision were improved using either a univariate model or multiple linear regression(MLR).More specifically,for the univariate model,the root-mean-square error of prediction(RMSEP),the determination coefficients(R^(2))and relative standard derivation(RSD)were improved from 3.30%,0.864 and 18.8%to 1.06%,0.986 and 13.5%,respectively;while for MLR,RMSEP,R^(2)and RSD were improved from 3.22%,0.871 and 26.2%to 1.07%,0.986 and 17.4%,respectively.These results prove that DSPTM can be used as an effective method to reduce matrix effects and improve repeatability by selecting reliable data.

Factors predicting sensory and motor recovery after the repair of upper limb peripheral nerve injuries

OBJECTIVE： To investigate the factors associated with sensory and motor recovery after the repair of upper limb peripheral nerve injuries. DATA SOURCES： The online PubMed database was searched for English articles describing outcomes after the repair of median, ulnar, radial, and digital nerve injuries in humans with a publication date between 1 January 1990 and 16 February 2011. STUDY SELECTION： The following types of article were selected： （1） clinical trials describ- ing the repair of median, ulnar, radial, and digital nerve injuries published in English; and （2） studies that reported sufficient patient information, including age, mechanism of injury, nerve injured, injury location, defect length, repair time, repair method, and repair materials. SPSS 13.0 software was used to perform univariate and multivariate logistic regression analyses and to in- vestigate the patient and intervention factors associated with outcomes. MAIN OUTCOME MEASURES： Sensory function was assessed using the Mackinnon-Dellon scale and motor function was assessed using the manual muscle test. Satisfactory motor recovery was defined as grade M4 or M5, and satisfactory sensory recovery was defined as grade S3＋ or S4. RESULTS： Seventy-one articles were included in this study. Univariate and multivariate logistic regression analyses showed that repair time, repair materials, and nerve injured were inde- pendent predictors of outcome after the repair of nerve injuries （P 〈 0.05）, and that the nerve injured was the main factor affecting the rate of good to excellent recovery. CONCLUSION： Predictors of outcome after the repair of peripheral nerve injuries include age, gender, repair time, repair materials, nerve injured, defect length, and duration of follow-up.

Clinical and pathological characteristics and prognosis of 132 cases of rectal neuroendocrine tumors

BACKGROUND Neuroendocrine tumors(NETs)frequently occur in the gastrointestinal tract,lung,and pancreas,and the rectum and appendix are the sites with the highest incidence.Epidemiology statistics show that an estimated 8000 people every year in the United States are diagnosed with NETs occurring in the gastrointestinal tract,including the stomach,intestine,appendix,colon,and rectum.The pathological changes and clinical symptoms of NETs are not specific,and therefore they are frequently misdiagnosed.AIM To investigate the clinical symptoms,pathological characteristics,treatment,and prognosis of rectal neuroendocrine tumors(RNETs)by analyzing the clinical and pathological data of 132 RNET cases at our hospital.METHODS All RNETs were graded according to Ki-67 positivity and mitotic events.The tumors were staged as clinical stages I,II,III,and IV according to infiltrative depth and tumor size.COX proportional hazard model was used to assess the main risk factors for survival.RESULTS These 132 RNETs included 83 cases of G1,21 cases of G2,and 28 cases of G3(neuroendocrine carcinoma)disease.Immunohistochemical staining showed that 89.4%of RNETs were positive for synaptophysin and 39.4%positive for chromogranin A.There were 19,85,23,and 5 cases of clinical stages I,II,III,and IV,respectively.The median patient age was 52.96 years.The diameter of tumor,depth of invasion,and pathological grade were the main reference factors for the treatment of RNETs.The survival rates at 6,12,36,and 60 mo after operation were 98.5%,94.6%,90.2%,and 85.6%,respectively.Gender,tumor size,tumor grade,lymph node or distant organ metastasis,and radical resection were the main factors associated with prognosis of RNETs.Multivariate analysis showed that tumor size and grade were independent prognostic factors.CONCLUSION The clinical symptoms of RNETs are not specific,and they are easy to misdiagnose.Surgery is the main treatment method.The grade and stage of RNETs are the main indices to evaluate prognosis.

Rapid screening and visual tracing of melamine in soybean meal by NIR microscopy imaging

Near infrared microscopy imaging fers the opportunity to explore not only what lkinds ofchemical species are present at micro-scale level but also where the chemical species would bepr esent.By revealing the spectral and spatial information,the technique can identify and localizeany interested component.This study investigates the feasibility of using Near infrared mi.croscopy imaging to detect melamine in soybean meal.The results showed that 6805 cm^(-1) is verysensitive for melamine but not for soybean meal,so can be used for univariate analysis,Singlewavelength image and peak integr ation image at 6805 cm^(-1) are simple and efective met hods todetect the melamine in soybean meal.Furthermore,Principal Component Analysis is applied todetect the melamine in soybean meal.

Prediction of Early Rebleeding and Mortality after Acute Esophageal Variceal Hemorrhage among Yemeni Patients in Major Hospitals—Sana’a

Background and aims: Acute variceal hemorrhage (AVH) is the most serious encountered complication of liver cirrhosis and carries high mortality rate. Several risk factors that predict early rebleeding and mortality have been studied and there is no similar study in our country, so the aim of this study was to identify the risk factors of early rebleeding and mortality after bleeding episode in cirrhotic patients in Yemen. Patients and Method: It was a prospective study of cirrhotic patients with AVH who were admitted to the main public hospitals in Sana’a between April 2014 and March 2015. Demographic information, medical histories, physical examination findings, and laboratory test results were collected. Endoscopic and pharmacologic treatment was performed. The patients were followed up since admission and up to 6 weeks for the occurrence of rebleeding and mortality after the acute attack. Univariate and multivariate analyses were performed to identify independent risk factors for rebleeding and mortality. Survival analysis was estimated using the Kaplan-Meier method. Result: A total of 102 patients were analyzed. 26 patients (25.5%) rebleeded within 6 weeks period. The predictive factors significantly associated with rebleeding within 6 weeks period in univariate analysis were clot on varix at index endoscope (P - 47.29, P = 0.001) and high serum bilirubin (- 1.19, P = 0.01). Sixteen patients died (15.7%) within 6 weeks period. Predictors of mortality with significant difference in univariate analysis were hypovolemic shock (P = 0.001), high WBCs count (P - 1.41, P - 1.40, P < 0.05) were independent risk factors for mortality within 6 weeks period. Conclusion: Early rebleeding in cirrhotic patients with AVH was associated with clot on varix at endoscope and high serum bilirubin more than 3 mg/dl. Early mortality rate was associated with high MELD score (≥19) and WBCs over 10.3 × 109/l.

Statistical approach to determination of overhaul and maintenance cost of loading equipment in surface mining

The purpose of this research was to develop a new approach in determination of overhaul and maintenance cost of loading equipment in surface mining. Two statistical models including univariate exponential regression (UER) and multivariate linear regression (MLR) were used in this study. Loading equipment parameters such as bucket capacity, machine weight, engine power, boom length, digging depth, and dumping height were considered as variables. The results obtained by models and mean absolute error rate indicate that these models can be applied as the useful tool in determination of overhaul and maintenance cost of loading equipment. The results of this study can be used by the decision-makers for the specific surface mining operations.